The present invention relates to a digital circuit for simultaneously generating digital sine- and cosine-function values for one and the same digital argument from any of the four quadrants of these functions.
In the journal "Electronik," 1971, No. 5, page 170, it is described how digital sine-function values can be stored in read-only memories with high resolution and accuracy, namely by using the trigonometric function which holds for the sine of the sum of two angles: sin(x+y)=sin(x)cos(y)+cos(x)sin(y).
Since the sine function is approximately equal to the angle for angle values between 0.degree. and about 5.degree., and the cosine function for angle values between 85.degree. and 90.degree., read-only-memory space can be saved.